The problem can evidently be solved by using a switched-mode power supply of the type known as a single-ended and push-pull converter. Such switched-mode power supplies are described in the book by O. Kilgenstein, Schaltnetzteile in der Praxis Switched-Mode Power Supplies in Practical Use! (1988), pages 9 to 13. The basic circuitry of various switched-mode power supplies is also described in W. Hirschmann and A Hauenstein, Schaltnetzteile Switched-Mode Power Supplies! (1990) pages 40 to 64. Also recommended for the galvanically isolated transmission of information to electronic units is the use of transformers or optical couplers.